/*
 * ====================================================================
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.http.client;

import java.util.Map;

import org.apache.http.Header;
import org.apache.http.HttpResponse;
import org.apache.http.auth.AuthScheme;
import org.apache.http.auth.AuthenticationException;
import org.apache.http.auth.MalformedChallengeException;
import org.apache.http.protocol.HttpContext;

/**
/**
 * A handler for determining if an HTTP response represents an authentication 
 * challenge that was sent back to the client as a result of authentication 
 * failure.
 * <p>
 * Implementations of this interface must be thread-safe. Access to shared
 * data must be synchronized as methods of this interface may be executed 
 * from multiple threads.
 *
 * @since 4.0
 */
public interface AuthenticationHandler {

    /**
     * Determines if the given HTTP response response represents 
     * an authentication challenge that was sent back as a result 
     * of authentication failure
     * @param response HTTP response.
     * @param context HTTP context.
     * @return <code>true</code> if user authentication is required,
     *   <code>false</code> otherwise.
     */
    boolean isAuthenticationRequested(
            HttpResponse response, 
            HttpContext context);

    /**
     * Extracts from the given HTTP response a collection of authentication 
     * challenges, each of which represents an authentication scheme supported
     * by the authentication host.   
     * 
     * @param response HTTP response.
     * @param context HTTP context.
     * @return a collection of challenges keyed by names of corresponding 
     * authentication schemes. 
     * @throws MalformedChallengeException if one of the authentication 
     *  challenges is not valid or malformed.
     */
    Map<String, Header> getChallenges(
            HttpResponse response, 
            HttpContext context) throws MalformedChallengeException;
    
    /**
     * Selects one authentication challenge out of all available and
     * creates and generates {@link AuthScheme} instance capable of
     * processing that challenge.
     * @param challenges collection of challenges.
     * @param response HTTP response.
     * @param context HTTP context.
     * @return authentication scheme to use for authentication.
     * @throws AuthenticationException if an authentication scheme
     *  could not be selected.
     */
    AuthScheme selectScheme(
            Map<String, Header> challenges, 
            HttpResponse response, 
            HttpContext context) throws AuthenticationException;
    
}
